Allow to command different things (pizza, bevarages) in a school cafeteria (open at lunch time) using uniquely the arrows of the keyboard and make the total to pay automatically

Allow to command different things (pizza, bevarages) in a school cafeteria (open at lunch time) using uniquely the arrows of the keyboard and make the total to pay automatically. At the end of the week, recapitulate all the totals of the week (before year 2000 !) .